Hi Jayalaxmi ,
All of us were new to Excel at some stage ; speaking for myself , I joined this forum in late 2011 , and by virtue of going through archived questions and answers , as well as by trying to answer questions myself , I have reached a stage where I can say I am fairly competent.
I would certainly recommend this route to anyone who is not an absolute novice ; if you are just starting on Excel , then it would be better if you started off by reading at least one book ; most people recommend any one by John Walkenbach or Bill Jelen or any of the other masters.
Even going through the Excel help on the functions will give you at least a basic idea of the syntax , which is the real starting point for using functions ; if you cannot get the syntax right , or you don't remember the basic purpose of each function , then you are not likely to use the right function for the right job.
The basic functions are :
MID , LEFT , RIGHT , TEXT , SUBSTITUTE , REPLACE
VLOOKUP , HLOOKUP , LOOKUP
INDEX , MATCH , OFFSET
SUMPRODUCT
SUMIF , COUNTIF , SUMIFS , COUNTIFS
LARGE , SMALL
INDIRECT
FREQUENCY
As you become more competent , you can easily add more functions , but I believe mastery of a set of 50 functions should easily qualify you as an expert , though if you wish to specialize in any domain , you should be good at the functions specific to that domain ; e.g. if you are going to specialize in statistics or accounting , there are at least a dozen functions in each of those domains.
More important than a knowledge of the individual functions is a knowledge of how they can be combined in different ways to achieve different purposes.
Over and above a good knowledge of these functions , you should also know two or three other aspects of Excel , such as CF and DV which you have already asked about , and others which you have not yet touched upon , such as Pivot Tables , Charts.
Though much can be accomplished with just the above , a minimum knowledge of VBA would be very helpful.
Narayan